This invention pertains to oil filters for filtering engine oil, and more particularly to replaceable oil filters which spin-on to a threaded oil inlet port in an engine. These spin-on oil filters are commonly used in internal combustion engines for vehicles such as motorcycles and cars.
Filtration of engine oil is very important for maintenance and upkeep of many engines, and particularly for motor vehicle engines. Dirt, metal particles and other contaminants are picked up by the oil in lubricating the engine. Removal of these particles from the engine oil is required to prevent excessive engine wear and increase engine life. The engine oil is generally pumped through a replaceable filter to clean the oil during engine operation. In many engines, the oil filter spins onto a threaded oil inlet port (i.e., the port where oil exits the filter and re-enters the engine) having an outer diameter of approximately 1/2 to 3/4 inches. A flat seal surface is provided on the engine, typically 3-4 inches in diameter, coaxially surrounding the inlet port. An oil outlet port (i.e., the port where oil exits the engine and enters the filter) is provided in the engine between the threaded inlet port and the seal surface. The filter screws onto the inlet port and, when fully seated, makes a seal against the exterior seal surface. During operation of the engine, oil flows into the filter through the outlet port, travels through the filtration material, and then exits the filter through the central threaded inlet port.
Engine oil filters should be regularly replaced before they become clogged or otherwise do not provide effective oil filtration. For many vehicles, oil filter replacement is recommended every 3,000 to 5,000 miles. Since the life of the vehicle may be 100,000 to 200,000 miles, a properly maintained vehicle will use 30-70 replaceable oil filters during its life.
Oil filters when removed from an engine contain a substantial amount of dirty engine oil, which is unwanted in the environment, and may further contain unnatural metal and/or plastic compositions which may take centuries to properly decompose. With current and upcoming anti-pollution legislation, the disposal of this large number of used oil filters is becoming more and more of a problem. Accordingly, it is desired to provide better ways to minimize the waste produced by used motor vehicle engine oil filters.
Several modular filter systems have been designed for use with the spin-on type oil filter station. For example, U.S. Pat. No. 5,066,391 to Faria discloses an oil filter having a filter element which is separate from an exterior canister. This allows for changing of the filter element without disposal of the canister. However, manufacture of previous modular oil filters is labor intensive and may require excessive machining and manufacturing time. Replacement of previous oil filter elements can be cumbersome and messy, particularly given the size constraints of the engine around the oil filtration station. Accordingly, a new design of oil filter is needed which will reduce oil filter waste, but still allow for simple removal and replacement of the filter element.